分析:d[i]表示到i点,最少的操作数 #include<cstdio> #include<cstring> #include<queue> #include<cstdlib> #include<algorithm> #include<vector> #include<cmath> using namespace std; typedef long long LL; +; const int INF=0x3f3f3f3f;…

POJ 1847 Tram (最短路径) Description Tram network in Zagreb consists of a number of intersections and rails connecting some of them. In every intersection there is a switch pointing to the one of the rails going out of the intersection. When the tram ent…

POJ 1847 最短路 每个点都有初始指向,问从起点到终点最少要改变多少次点的指向 *初始指向的那条边长度为0,其他的长度为1,表示要改变一次指向,然后最短路 =========高亮!!!==========数组要开n^2的QAQ #include <iostream> #include <cstdio> #include <queue> using namespace std; #define SZ 10005//开n^2的数组!! #define INF 1e9+…

http://poj.org/problem?id=1847 这道题题意不太容易理解,n个车站,起点a,终点b:问从起点到终点需要转换开关的最少次数 开始的那个点不需要转换开关 数据: 3 2 1//第一个数车站总数3,第二个数起点2,第三个数终点1 2 2 3//第一个数有2个点可到达,两个点分别是2(不需要转换开关),3(需要转换开关) 2 3 1 2 1 2可转化为最短路来写,转换开关次数当做最短路径 #include<stdio.h> #include<stdlib.h>…

Tram Time Limit: 1000MS Memory Limit: 30000K Total Submissions: 14630 Accepted: 5397 Description Tram network in Zagreb consists of a number of intersections and rails connecting some of them. In every intersection there is a switch pointing to the o…

Tram 题目链接: http://acm.hust.edu.cn/vjudge/contest/122685#problem/N Description Tram network in Zagreb consists of a number of intersections and rails connecting some of them. In every intersection there is a switch pointing to the one of the rails goi…

Tram Time Limit: 1000MS   Memory Limit: 30000K Total Submissions: 12005   Accepted: 4365 Description Tram network in Zagreb consists of a number of intersections and rails connecting some of them. In every intersection there is a switch pointing to t…

Description Tram network in Zagreb consists of a number of intersections and rails connecting some of them. In every intersection there is a switch pointing to the one of the rails going out of the intersection. When the tram enters the intersection…

题意:有向图有N个点,当电车进入交叉口(某点)时,它只能在开关指向的方向离开. 如果驾驶员想要采取其他方式,他/她必须手动更换开关.当驾驶员从路口A驶向路口B时,他/她尝试选择将他/她不得不手动更换开关的次数最小化的路线. 编写一个程序,该程序将计算从交点A到交点B所需的最小开关更改次数.第i个交点处的开关最初指向列出的第一个交点的方向. 分析:对于某点i,去往其直接可到达的点列表中的第一个点时不需要更换开关,等价于边长为0:而其他的点需要更换开关,等价于边长为1.dijkstra裸题. #in…

题目传送门 题意:这题题目难懂.问题是A到B最少要转换几次城市.告诉每个城市相连的关系图,默认与第一个之间相连,就是不用转换,其余都要转换. 分析:把第一个城市权值设为0, 其余设为0.然后Floyd跑一下,得到A到B最少转换几次.有点水 #include <cstdio> #include <cstring> #include <algorithm> using namespace std; const int N = 1e2 + 5; const int INF =…